Alloy



Patented July 12, 1932 v UNITED STATES PATENT OFFICE PA'UL D. MERICA, OFWESI'FIELD, AN D JAMES B. VAI IICK, OI ELIZABETH, m M,

ASSIGNOBS, BY mm ASSIGNMENTS, TO THE INTERNATIONAL NICKEL comm, mo, OFNEW YORK, N. Y.) A CORPORATION 01' DELAWARE ALLOY Io Drawing.

Our invention relates to alloys and particularly to cast iron alloysadapted to resist corrosion or oxidation. We have discovered that ifnickel, copper and chromium be added as alloying in e ients to castiron, particularly within t e proportlons hereinafter recited, an alloyis produced which can becast and handled in the foundry insubstantiallythe same way as ordinary gray cast 1ron. In

making the alloy we add to cast 1ron havlng the usual carbon content ofcast iron namely from about 2% to 4% of carbon, nickel, copper andchromium. The nickel and copper preferably added as an alloy in amountfrom u about 5% up to about 5.0%, the ratio of n1ck el to copper in saidalloy beir ig preferably 1n the neighborhood of 2.2%. e chromium isadded preferably from up to 15% and the added alloying metals alsopreferably conlo tain from 1.5 to 4% of carbon and from to 3% ofsilicon.

For example, good results are obtamed with a cast iron allo containin ofthe alloy known as onel meta (in WlllCll the ratio of nickel to copperis 2.2), 2% of chromium, 3% of carbon and 2% of silicon. The preferredrange of alloy is as follows:

Nickel 10-20%, copper 210% (or cop er greater than 2% but less than ofthe mo el content), carbon 23.5%, silicon 0.252.5%, chromium up to 5%,manganese and other elements as usual for cast iron. 7

The alloy may be cast in sand molds to form a gray cast iron casting, orit may be cast against a chill to form white iron. The shrinkage of suchcastings is about the same as that of ordinary cast iron. When castunder the ordinary conditions of making gray cast iron castings, thecarbon is partly in the graphitic state so that the castings are grayand readily machinable. Such castings have a transverse strengthcomparable with that of an ordinary 2% silicon gray iron casting. Thus,test bars show 130 Brinell test and 3000 lbs. in transverse strength;

Castings thus made are, however, greatly superior to ordinary cast ironin corrosion resistant properties and are comparable in this respectwith Monel metal castmgs or the ordinary cast brasses or bronzes. Thus,

Application fled July 8,1988; Serial 80,180,515.

when our casting is subjected to 5% sulphuric acid'aerated at ordinarytemperatures, the corrosion is about at the rate of 350 milligrameser-square decimeter per da This is about t e same as that of lead, ronzeor Monel metal while plain cast iron shows aboult 30,000 milligrams persquare decimeter per ay.

When our preferred alloy is subjected to aerated 3% sodium chloridesolution it shows a loss of 50 milligrams per square decimeter per dayas compared to 300 for ordinary cast iron. Such an alloy will only rustsuper- I ficially and appears to be quite stable toward ordinaryatmospheric and other corroding influences such as are ordinarilyencountered in industrial ractice. The castings are also amenable to eattreatment to render them within suitable composition limits either softor hard, with corresponding variations in malleability and toughness.

The alloys are particularly adapted for castings of either the gray ironor chilled iron type where anti-corrosive material is needed such forexample as in valves, chemical apparatus, etc. Among othercharacteristic advantages of our alloy, particularly within thepreferred range, are the following:the alloy is substantially 'nonmagnetic at ordinary and at high temperatures; it has a high electricalresistance which is es pecially useful in the absence of magnetism; ithas a high coeflicient of thermal expansion from room temperature up toabout 300 (3., which is approximately .000018 per degree centigrade; itis moderately heat resistant, that is, relatively stable athighertemperatures up to about 1500 F., atthe same time bein substantiallyfree from the phenomenon 0 growth.

It canbe readily welded by the usual autogenous methods and is moresatisfactory than iron for this purpose as it is not thereby hardened inthe weld area as is ordinary cast iron. The above properties 95 make thealloy valuable for many purposes,

such as castings subjected to high temperatures where scaling, should bekept at-a minimum and volume stability is important. It I is valuablefor electrical castings especially where the absence of magnetism isimportant, and its high coefiicient of thermal expansion fits it formechanical construction where it is to be associated with other highexpansion metals or alloys, such as aluminum, brass or similar alloys.

Other ingredients may be added such as aluminum and manganese. Themanganese may be from .3 to 10% and the aluminum from nothin up to about3%.

While we ave described a preferred proportion of our inventionit will beunderstood that the invention is not limited thereto but may be variedwithin the scope of the following claims.

We claim:

' 1. An alloyed cast iron containin more than 50% of iron having from 2%an u to about 4% carbon, and also containing nic el,

. copper and chromium, the nickel being from 10-20%, the copper beingover 1% but less than 7 of the nickel and the chromium from a materialercentage to not over 10%.. v

2. An a oy cast iron containing more than about of iron, carbon fromabout 2% to about.3.5% nickel about 10% to about 20%, copper about 2% toabout 10%, chromium from a material rcentage up to about 5% and siliconfrom a out 0.25% to about 3.0%.

3. An alloy cast iron as set forth in claim 2, in which the nickel ispresent to an extent of approximately twioethe copper content.

In testimony whereof we have hereunto set our hands. 4 7 PAUL D.MIERICA.

JAMES S. VANIOK.

